Solve for $x$ and $y$ by deriving an expression for $y$ from the second equation, and substituting it back into the first equation. $\begin{align*}-8x-3y &= 8 \\ -x-y &= -4\end{align*}$
Explanation: Begin by moving the $x$ -term in the second equation to the right side of the equation. $-y = x-4$ Divide both sides by $-1$ to isolate $y$ $y = {-x + 4}$ Substitute this expression for $y$ in the first equation. $-8x-3({-x + 4}) = 8$ $-8x + 3x - 12 = 8$ Simplify by combining terms, then solve for $x$ $-5x - 12 = 8$ $-5x = 20$ $x = -4$ Substitute $-4$ for $x$ back into the top equation. $-8( -4)-3y = 8$ $32-3y = 8$ $-3y = -24$ $y = 8$ The solution is $\enspace x = -4, \enspace y = 8$.